Backup iphone via itunes

found a solution:

Re: iOS12 has issues with reconizing devices in iTunes

Re: After installing iOs12, iTunes on my Macbook doesn't recognize my iPhone 5s anymore

1. in the mac App Store go to Preferences and activate all automatic update options (maybe except for MacOS)
2. go to http://www.apple.com/itunes/download and download the current iTunes for mac (12.8)
3. close itunes completely (command-Q) but leave the iphone or ipad having iOS 12 connected via USB
4. install the downloaded iTunes pkg installer: the installer will detect the iOS 12 iphone and ask for permission to download an additional update.
5. when the installation is compete the iOS 12 device will show up again in iTunes

I have the same problem -- none of the iOS 12 devices will show up in iTunes 12.8, so I can't back up. However, I was able to back up via the USB cable using the free Apple app called Apple Configurator 2 from the Mac App Store. Link below. When you connect the device via USB, it will show up in this app, and then you can select it and press the "Backup" button that has an orange arrow pointing up. You can also restore from a backup using the Actions menu - see screenshot #2 below.

Apple Configurator 2 on the Mac App Store

So you can't do a restore because it's not showing the backup? To check if the backup is there, go to Preferences -> Devices and it should be listed.

If you don't want to do a restore but just want files, it is possible to get the data off without doing a restore with software like iExplorer. Just google "iPhone backup locations" and it will tell you where the files are stored on your Mac or PC.

Thanks

iOS 12 devices need iTunes 12.9 or above to be seen in iTunes. High Sierra's iTunes is currently 12.8. Mojave's iTunes is 12.9. So, iOS 12 devices are seen in Mojave but not High Sierra or below.

Apple needs to release a 12.9 version for High Sierra or lower. Not every wants or needs to upgrade to Mojave on 9/24.

I can't get this to work as Majave won't load on my Mac only High Sierra. How long does Apple typically take to correct these blunders with a patch does anyone know? Their call centre just told me could be up to 2 weeks!!! and basically to buy a new Mac that runs Majave because a 7 year old Mac (that ran perfectly until this) is now obsolete :-(

MrsLevHead, both solutions I mentioned above will work on High Sierra. Apple Configurator 2 is the least disruptive but will only back up, not sync the media library.